Up to now, to applicant's knowledge, it has been impossible to fire a frangible projectile of the above-noted type in an automatic or semi-automatic manner. If the frangible projectile is fitted to a conventional cartridge, the breech block of an automatic weapon will not retract to its cocked position if the amount of gun powder used is low enough to prevent rupture of the frangible projectile within the gun barrel. If the amount of powder is high enough to fully recoil the breech block, then detonation of the powder will cause rupture of the projectile within its cartridge or within the gun barrel.